Clamping device for an electrochemical cell stack

ABSTRACT

A clamping device for an electrochemical cell stack is provided. The clamping device can include a first plate and a second plate. The second plate can be positionable relative to the first plate such that a space between the first plate and the second plate can be sized to receive an electrochemical cell stack. The device also can include a coupling member coupling the first plate to the second plate. At least one of the first and second plates can be movable away from the other plate. The coupling member can have a first end portion and a second end portion. The device further can include an elastic member disposed between the first end portion and the second end portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/195,368, filed Mar. 3, 2014, which claims the benefit of U.S.Provisional Patent Application No. 61/785,728, filed Mar. 14, 2013. Theentirety of each of the above referenced applications is herebyincorporated by reference.

BACKGROUND

1. Field

The present disclosure relates generally to clamping devices. Inparticular, the present disclosure relates to clamping devices forelectrochemical cell stacks.

2. Description of the Related Art

A lithium ion battery typically includes a separator and/or electrolytebetween an anode and a cathode. In some of batteries, the separator,cathode and anode materials are individually formed into sheets orfilms. Sheets of the cathode, separator and anode are subsequentlystacked or rolled with the separator separating the cathode and anode(e.g., electrodes) to form the battery. For the cathode, separator andanode to be rolled, each sheet must be sufficiently deformable orflexible to be rolled without failures, such as cracks, brakes,mechanical failures, etc. Typical electrodes include electrochemicallyactive material layers on electrically conductive metals (e.g., aluminumand copper). For example, carbon can be deposited onto a currentcollector (e.g., a copper sheet) along with an inactive binder material.Carbon is often used because it has excellent electrochemical propertiesand is also electrically conductive. Electrodes can be rolled or cutinto pieces which are then layered into stacks. The stacks are ofalternating electrochemically active materials with the separatorbetween them.

In order to increase the volumetric and gravimetric energy densities oflithium-ion batteries, silicon has been proposed as the active materialfor the negative electrode. However, during cycling, silicon particlesin the anode active material expand upon charging. This expansion candeform the metal foil used as current collectors. Since the layers ofthe cell stack are confined in a tight region, the expansion can resultin warping or deformation of the metal foil, thus reducing the contactarea between layers in the battery stack. As a result, the ability of abattery to accept and release electrical charge may be severelyaffected. Thus, preventing the electrode from deformation could serve toreduce the irreversible capacity and improve cycle life.

SUMMARY

In certain embodiments, a clamping device for an electrochemical cellstack is provided. The clamping device can include a first plate and asecond plate positionable relative to the first plate such that a spacebetween the first plate and the second plate is sized to receive anelectrochemical cell stack. The clamping device can also include acoupling member coupling the first plate to the second plate. At leastone of the first and second plates can be movable away from the otherplate. The coupling member also can have a first end portion and asecond end portion. Furthermore, the clamping device can include anelastic member disposed between the first end portion and the second endportion.

In some embodiments, the variation of the distance between the first andsecond plates correlates with the expansion of the electrochemical cellstack. At least one of the end portions of the coupling member can beconfigured to set an applied pressure on the electrochemical cell stack.The clamping device can also be configured to reduce deformation of anelectrode in the electrochemical cell stack upon charging. In addition,the elastic member can be configured to be compressed during thecharging of the electrochemical cell stack, thereby reducing theincrease in pressure on the electrochemical cell stack exerted by thefirst and second plates. Reducing the increase in pressure can result ina substantially constant pressure on the electrochemical cell stack.

In some embodiments, the elastic member is configured to be compressedduring the charging of the electrochemical cell stack, thereby reducingvariations in pressure on the electrochemical cell stack due to theexpansion of the electrochemical cell stack. The elastic member cancomprise a spring, a plunger, an elastic band, a pneumatic piston, orfoam. The coupling member can comprise a fastener, a spring clamp, or aC-clamp. At least one of the first or second end portions can comprise aplurality of nuts or a plurality of fastener heads.

In further embodiments, a method of reducing deformation of an electrodein an electrochemical cell stack is provided. The method includespositioning the electrochemical cell stack between the first and secondplates; and adjusting the end portion of the coupling member to set anapplied pressure on the electrochemical cell stack.

In some embodiments, the method can include charging the electrochemicalcell stack. Also, the electrochemical cell stack can be positionedbetween the first and second plates prior to charging theelectrochemical cell stack for the first time. The method can furtherinclude removing the electrochemical cell stack after cell formation orcell pretreatment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph of an example clamping device for anelectrochemical cell stack in accordance with certain embodimentsdescribed herein;

FIG. 2 is a schematic of the example clamping device shown in FIG. 1;

FIG. 3A is a plot of the force on an electrochemical cell stack as afunction of cell expansion of an electrochemical cell stack placed in afixed-gap clamping device;

FIG. 3B is a plot of the force on an electrochemical cell stack as afunction of cell expansion of an electrochemical cell stack placed in aclamping device of certain embodiments described herein;

FIG. 4 is a photograph of a warped anode in an electrochemical cellstack;

FIG. 5 is a photograph of a non-warped anode of a electrochemical cellstack placed in a clamping device of certain embodiments describedherein; and

FIG. 6 illustrates an example method of reducing deformation of anelectrode in an electrochemical cell stack.

DETAILED DESCRIPTION

Anode electrodes currently used in the rechargeable lithium-ion cellstypically have a specific capacity of approximately 200 milliamp hoursper gram (including the metal foil current collector, conductiveadditives, and binder material). Graphite, the active material used inmost lithium ion battery anodes, has a theoretical energy density of 372milliamp hours per gram (mAh/g). In comparison, silicon has a hightheoretical capacity of 4200 mAh/g. Silicon, however, swells in excessof 300% upon lithium insertion. Because of this expansion, anodesincluding silicon should be allowed to expand while maintainingelectrical contact between the silicon particles. However, as anelectrochemical cell stack expands, the expansion can be non-uniform,resulting in thickness variation in the cell stack and deformation.

This disclosure describes certain embodiments of a clamping device foran electrochemical cell stack configured to reduce deformation of anelectrode that expands in a cell stack upon charging. The cell stackscan include graphite, silicon-based, tin-based or other alloy-basedelectrodes. For example, the clamping device can comprise a first plateand a second plate. The second plate can be positionable relative to thefirst plate such that a space between the first plate and the secondplate is sized to receive an electrochemical cell stack. The clampingdevice also can comprise a coupling member coupling the first plate tothe second plate. At least one of the first and second plates can bemovable away from the other plate. For example, at least one of thefirst and second plates can be movable about the coupling member.

If at least one of the first and second plates were not movable awayfrom the other plate, the first and second plates can exert anincreasing pressure onto the cell stack upon expansion of the cell stackduring charging. Left uncontrolled, if a high enough pressure isreached, the cell stack could be damaged, e.g., shorting of the cellstack. However, in certain embodiments, because at least one of thefirst and second plates can be movable away from the other plate, someof the pressure exerted by the first and second plates onto the cellstack can be relieved and also controlled.

For example, in some embodiments, only one of the first and the secondplates is movable as the cell stack expands. In other embodiments, bothplates are movable as the cell stack expands. The variation of thedistance between the first and second plates can correlate with theexpansion of the cell stack.

In some embodiments, the coupling member can have a first end portionand a second end portion. The clamping device can further include anelastic member disposed between the first end portion and the second endportion. At least one of the end portions of the coupling member can beconfigured to set an applied pressure on the cell stack. For example,the elastic member can be configured to be compressed during thecharging of the cell stack. As the elastic member is compressed, theincrease in pressure on the cell stack exerted by the first and secondplates can be reduced. In some instances, the reduced increase inpressure by the first and second plates can result in a slight variationin pressure (or a substantially constant pressure) on the cell stack,and thereby reducing the thickness variation and/or deformation of thecell stack due to non-uniform expansion.

As described herein, certain embodiments of the clamping device caninclude a first plate and a second plate. In some embodiments, the firstplate can be made of substantially the same material as that of thesecond plate. In other embodiments, the first plate can be made ofdifferent material than that of the second plate. The materials caninclude metal (e.g., carbon steel or aluminum) and/or a polymer (e.g.,polypropylene or an epoxy). The materials can also include an insulatingmaterial. The cross-sectional shape of at least one of the first andsecond plates can be square, rectangular, circular, ovular, or polygonal(e.g., pentagonal, hexagonal, octagonal, etc.). The second plate can bepositionable relative to the first plate such that there is a spacebetween the first and second plates. Because the space can be sized toreceive an electrochemical cell stack, the dimensions of the first andsecond plates can be sized and shaped so as to be able to house a cellstack between the first and second plates. Thus, the dimensions of thefirst and second plates can depend on the size and shape of the cellstack. Furthermore, the thicknesses of the first and second plates canbe sized to reduce bending of the first and second plates upon chargingof the cell stack. For example, the thicknesses of the first and secondplates can be between about 0.5 cm and about 0.8 cm, e.g., about 0.6 cm,about 0.65 cm, or about 0.7 cm. In some embodiments, the shape anddimensions of the first plate can be substantially the same as the shapeand dimensions of the second plate. In other embodiments, the shape anddimensions of the first plate can be different than the shape anddimensions of the second plate.

In some embodiments, the space between the first and second plates canbe sized to receive more than one cell stack. For example, a pluralityof cell stacks can be placed side by side or stacked on top of eachother between the first and second plates. In such embodiments, multiplecell stacks can utilize the same clamping device (e.g., the same elasticmember to maintain similar or substantially the same set pressures onthe cell stacks). Furthermore, the clamping device can also include morethan the first and second plates, e.g., multiple plates stacked on topof each other. The space between two plates can be sized to each receiveat least one cell stack. In such embodiments, several cell stacks canalso utilize the same elastic member. Thus, a plurality of cell stackscan be placed between the first and second plates with or withoutadditional plates and/or spacers.

In some embodiments, the coupling member extends through a bore in thefirst plate and/or the second plate. For example, the coupling membercan be any extending structure having a longitudinal length capable ofcoupling the first and second plates. In some embodiments, the couplingmember is fixed or seated in the first or the second plate. For example,the coupling member may be a post/rod with one end fixed in the first orthe second plate, or the coupling member may be a screw or a post with athreaded portion screwed directly into the first or the second plate. Inother embodiments, the coupling member extends through a first bore inthe first plate and a second bore in the second plate. In someembodiments, the coupling member may be a fastener such as a screw, abolt, or a rod/post. In some embodiments, the rod/post may or may notcomprise a threaded portion or a textured portion. In other embodiments,the coupling member may comprise a clamp, e.g., a C-clamp. In someembodiments, the clamping device may comprise one or more couplingmembers.

In some embodiments, the first and the second end portions areindependently a nut, a head (e.g., a screw head, a bolt head, orequivalent), a post clamp, a plate (e.g., the first or second plate, oran additional third plate), or part of a C-clamp. The end portions arealso configured to prevent the movable plate(s) from being decoupledfrom the coupling member. In some embodiments, the end portions areconfigured to set an applied pressure on the cell stack between thefirst and the second plates. For example, the set pressure can take intoconsideration, e.g., help compensate for, the non-uniform thicknessvariation of the cell stack. In embodiments where a plurality ofcoupling members are used, the pressure set by one coupling member canbe different than the pressure set by another coupling member.

The clamping device further can comprise an elastic member disposedbetween the first end portion and the second end portion. The elasticmember may be disposed between the first plate and the first endportion, between the second plate and the second end portion, or betweenthe first plate and the second plate. The elastic member can have aspring constant, and may be an expansion member or a compression member.In some embodiments where the elastic member is disposed between thefirst plate and the first end portion and/or between the second plateand the second end portion, the elastic member may be a compressionmember, which is configured to push the first or the second plates awayfrom the first or the second end portion, respectively. In someembodiments where the elastic member is disposed between the first andthe second plates, the elastic member may be an expansion member, whichis configured to pull the first and the second plates toward each otheror exert force on the two plates to cause the plates to be pushed towardeach other. In some embodiments, the elastic member may comprise aspring (including expansion spring and compression spring), a plunger,an elastic band, a pneumatic piston, or foam. In some embodiments, theelastic band (e.g., a rubber band) can be disposed around the first andsecond plates. The elastic band can be configured to allow the at leastone of the first and second plates to move away from the other plateupon expansion of the electrochemical cell stack. At least one of thefirst or second plates can be configured to compress the elastic band toset an applied pressure on the cell stack.

In another embodiment, the end portions can include parts of a C-clampholding two plates at a fixed distance relative to each other. A thirdplate and an elastic member can be inserted in between the two fixedplates.

FIG. 1 is a photograph of an example clamping device in accordance withcertain embodiments described herein. FIG. 2 is a schematic of theexample clamping device shown in FIG. 1 that can be used to confine andexert pressure on the cell stack during cycling. The clamping device 200can include a first plate 210 and a second plate 220. The second plate220 can be positionable relative to the first plate 210 such that aspace 230 between the first plate 210 and the second plate 220 is sizedto receive an electrochemical cell stack 240. The clamping device 200can also include a coupling member 250 (e.g., a threaded bolt) couplingthe first plate 210 to the second plate 220. At least one of the first210 and second 220 plates can be movable away from the other plate. Forexample, the second plate 220 can move upward along the coupling member250 as the cell stack 240 expands. In some embodiments, the first plate210 may also be movable about the coupling member 250. For example, thefirst plate 210 may move downward along the coupling member 250 as thecell stack 240 expands.

The coupling member 250 can have a first end portion (on an end portionopposite to 255) and a second end portion 255 (e.g., a bolt head). Theclamping device 200 can further include an elastic member 260 (e.g., aspring) disposed between the first end portion and the second endportion 255. As the cell stack 240 within the clamping device 200expands on cycling, the elastic member 260 can allow the second plate220 to move along the coupling member 250 to a distance relative to thefirst plate 210. The variation of the distance between the first plate210 and the second plate 220 can correlate with the expansion of thecell stack 240.

The second end portion 255 of the clamping device 200 can be configuredto compress the elastic member 260. Thus, the second end portion 255 ofthe coupling member 250 can be configured to set an applied pressure onthe cell stack 240, e.g., by tightening or loosening the bolt head. Inthe example clamping device 200 shown in FIG. 2, the coupling member 250comprises four bolts 255. Each bolt 255 can be tightened or loosenedindependently. Thus, each elastic member 260 can be compressedindependently to set an applied pressure on the cell stack 240, e.g., toreduce the increase in the applied pressure on the cell stack 240exerted by the first 210 and second plates 220 and/or to reducevariations in pressure on the cell stack 240 due to the expansion of thecell stack 240.

By applying a pressure that considers the thickness variations uponexpansion, more consistent electrochemical behavior can result. In someembodiments, the variations in pressure can be reduced so that theapplied pressure slightly varies or is substantially constant. FIG. 5 isa photograph of a non-warped anode in an electrochemical cell stackplaced in a clamping device of certain embodiments described herein.

In various embodiments, as shown in the example embodiment of FIG. 2,the coupling member 250 can include a plurality of coupling members. Forexample, the coupling member 250 includes four threaded bolts 251extending through bores 215 within the corners of at least the secondplate 220. The first plate 210 may be threaded and the coupling members250 may thread directly into the first plate 210. In some embodiments,bolts may be disposed below the first plate 210. The first plate 210 maybe movable on the coupling member 250. As described herein, othercoupling members 250 can be contemplated.

Furthermore, although the clamping device 200 shown in FIGS. 1 and 2includes four separate coupling members 250 disposed in the corners ofthe first 210 and extending through the bores in the second 220 plates,the coupling member 250 can include less than four (e.g., three, two, orone) coupling members or more than four (e.g., five, six, seven, eight,etc.) coupling members disposed about any location of the first 210 andsecond 220 plates (e.g., not necessarily in the corners). As an example,there could be additional coupling members 250 disposed along one ormore edges of the first 210 and second 220 plates in addition to orinstead of within the corners of the first 210 and second 220 plates. Inother embodiments, there could be fewer than four coupling members 250,e.g., two coupling members 250 disposed on opposite sides from eachother. In some such embodiments, the coupling members 250 may have adimension (e.g., a width or a major axis) that is substantially similarto a dimension (e.g., a length) of the first 210 and second 220 plates.Various configurations are possible.

FIGS. 1 and 2 illustrate an elastic member 260 comprising a plurality ofsprings. The springs are disposed between the first and second endportions. In this example, the springs are also disposed between thesecond end portion 255 (e.g., bolt heads) and the second plate 220. Asthe cell stack 240 within the clamping device 200 expands duringcycling, the springs can allow the second plate 220 to move a distance(e.g., correlating to the expansion of the cell stack 240) along thecoupling members 250 (e.g., bolts). The bolt heads can be configured tocompress the springs. For example, the force load on the springs can beadjusted to set an applied pressure on the cell stack 240 by tighteningor loosening the bolt heads. In some embodiments, the bolt heads can betightened until the springs reach a desired length, which can correlateto an applied pressure on the cell stack 240. By compressing the elasticmember 260, the position of the second plate 220 relative to the firstplate 210 can also be adjusted. In certain embodiments, the appliedpressure can be different for two or more coupling members 250. Also,the adjusted position of the second plate 220 relative to the firstplate 210 need not be in the same position prior to expansion. In someembodiments, the length of each spring, for example, can be measuredwith calipers to increase consistency.

As described herein, the increase in pressure on the cell stack 240exerted by the first 210 and second 220 plates can be reduced. In someembodiments, the reduced increase in pressure can result in appliedpressure on the cell stack 240 that varies slightly or that issubstantially constant. In some embodiments, if the applied pressure istoo high (e.g., greater than about 400 psi), the electrolyte may besqueezed out of the cell stack 240. Additional damage can also occur tothe components of the cell stack 240, including shorting of the cellstack 240. Conversely, in some embodiments, if the applied pressure istoo low (e.g., less than a pressure between about 10 and 40 psi forcertain pouch cells), the warping of the current collector may not becontained and the electrode foils of the current collector may deform.In various embodiments, the applied pressure on the cell stack 240 canbe between about 10 psi and about 400 psi, between about 20 psi andabout 400 psi, between about 30 psi and about 400 psi, between about 40psi and about 300 psi, between about 50 psi and about 300 psi, betweenabout 60 psi and about 300 psi, between about 70 psi and about 300 psi,between about 80 psi and about 300 psi, between about 90 psi and about300 psi, or between about 100 psi and about 200 psi.

The clamping device 200 in accordance with certain embodiments can alsoinclude an interfacial material (not shown) between the first 210 andsecond 220 plates. For example, the interfacial material can be placedbetween the cell stack 240 and at least one of the first 210 and second220 plates. The interfacial material can conform to the surface of thecell stack 240 and can be made of polyethylene sheet, polypropylenesheet, PTFE sheet, paper, paperboard, natural rubber, silicone rubber,foam, or felt. The interfacial material can help spread the pressuremore evenly. In addition, the interfacial material can reduce and/orsubstantially eliminate damage caused by the force of the elastic member260 compressing on the thickest portion of the cell stack 240. Thisinterfacial material may also allow additional adjustment to account forthe cell thickness variation which results in non-uniform pressureduring cycling.

The advantage of the clamping device that allows for applied pressureadjustment (i.e., adjustable clamping device) can be seen by comparingthe electrochemical cells that were cycled in the adjustable clampingdevices with the cells that were cycled in fix-gap clamping devices.When a fix-gap clamping device is used, the cell stack is confined in afixed space. As the cell stack expands during cycling, theforce/pressure exerted on the cell stack would quickly increase withincreasing expansion. Expansion during cycling is typically not uniform,resulting in a thickness variation of the cell stack, which may resultin non-uniform pressure exerted on the cell stack. For example, a groupof cells cycling with a fixed-gap clamping device had a standarddeviation of about 12% of their discharge capacity, while a group ofcells cycling with a clamping device 200 in according with certainembodiments described herein had a standard deviation of about 3% oftheir discharge capacity.

The force (thus, applied pressure) on the cells as a function of cellexpansion during the cycling in an adjustable clamp can be compared tocycling in a fix-gap clamp. FIG. 3A is a plot of the force on anelectrochemical cell stack as a function of the cell expansion in afixed gap clamping device. As shown in FIG. 3A, as the cell stackexpands during charging, the force (and thus, pressure) exerted on thecell stack by the clamping device increases quickly (variessignificantly) upon expansion. In the exemplified embodiment, the forceincrease is not linear, but substantially exponential. The high pressureon portions of the cell can damage the cell, likely causing failuressuch as shorting and/or rupture of the cell.

FIG. 3B shows a plot of the force on an electrochemical cell stack as afunction of the cell expansion in an adjustable clamping device. As thecell expands during charging, the increase of the force exerted on thecell stack is much slower (slightly varies) compared to that of the cellin a fix-gap clamping device. In some embodiments, the increase in theforce is substantially linear, but with a low slope. In otherembodiments, the force on the cell stack could be substantially constantduring cell expansion.

As described herein, reducing the increase in applied pressure on thecell stack 240 by two plates can result in an applied pressure on thecell stack 240 that considers the thickness variation of the cell stack240 upon expansion. In some instances, the increase in applied pressureon the cell stack 240 can be reduced such that the applied pressureslightly varies or becomes substantially constant upon cell expansion.Reductions in the increase in applied pressure can result in a moreconsistent electrochemical behavior.

As described herein, various embodiments of clamping devices 200 canreduce the amount of warping and deformation on the electrode or currentcollector foil by reducing/slowing the increase exerted by the first 210and second 220 plates and/or by reducing the variation in the appliedpressure due to the expansion of the cell stack 240. As can be seen inFIG. 4, the copper foil is wrinkled or deformed following cycling of thecell stack. The amount of wrinkle or deformation on the copper foilcould be greatly minimized when the cell stack is cycled in the clampingdevice 200, as seen in FIG. 5. Furthermore, the clamping device 200 ofcertain embodiments can be left on the cell stack 240 substantiallywithout affecting the cycle life of the cell stack 240. Certainembodiments have been tested on electrochemical cells containingsilicon-based electrodes as well as graphite electrochemical cells.

FIG. 6 illustrates an example method of reducing deformation of anelectrode or current collector in an electrochemical cell stack. In theexample method 300, as shown in block 310, the method 300 can includeproviding a clamping device 200. The clamping device 200 can be theclamping device 200 as shown in FIGS. 1 and 2 and as described herein.The method 300 can also include positioning the electrochemical cellstack 240 between the first 210 and second 220 plates. Furthermore, themethod 300 can include adjusting the end portion 255 of the couplingmember 250 to set an applied pressure on the electrochemical cell stack240. As an example, the applied pressure on the electrochemical cellstack 240 can be set to help compensate for the non-uniform thicknessvariation during charging of the cell stack 240. As a result, the amountof warping and deformation of the current collector can be reduced. See,e.g., FIG. 5.

In some methods, the timing of the use of the clamping device 200 can beimportant. For example, in order to reduce electrode or currentcollector foil deformation, the cell stack 240 may be clamped before thefirst charge occurs (e.g., also known as formation charge). If theclamping device 200 is used for the first time after the first formationcharge occurs, the current collector foil may irreversibly deform (e.g.,may be unable to return to its original geometry). Thus, in certainembodiments, the method 300 can further include positioning the cellstack 240 between the first 210 and second 220 plates prior to chargingthe cell stack 240 for the first time.

Cell formation occurs when the cell is treated after building the cell(e.g., to help the cell perform well throughout its life). Many times,cell formation can refer to the first charge of a cell. In someinstances, the cell formation procedure can be more complicated. Forexample, cell formation can include charging of the cell at a rate ofC/20, cycling the cell three times by charging at the rate of C/2,holding the voltage at the charge voltage (e.g., 4.2V) until the currentdrops to C/20, and then discharging at the rate of C/5. These types ofprocedures can be done while the cell is clamped with certainembodiments described herein. For pouch or can cells with a good polymeradhesion technology, the clamping device can be removed after thepre-treatment of the cell is finalized. For pouch or can cells withoutsufficient polymer adhesion technology, the clamping device can remainon the cell, e.g, the applied pressure could be the same as during thepre-treatment or can be reduced. Other cell pre-treatment conditionsthat may be used before removing the clamping device includes treatmentsto the cell that include heating, pressing, and or heating and pressing.

In some embodiments, positioning the cell stack 240 between the first210 and second 220 plates can include positioning a cell stack 240 thatincludes an electrode having silicon. In other embodiments, positioningthe cell stack 240 between the first 210 and second 220 plates caninclude positioning a cell stack 240 that includes an electrode havinggraphite. Additionally, it is possible to include more than one cellstack 240 per clamping device 200. For example, more than one cell stack240 can be placed side by side or in multiple layers, as long as thepressure on the cell stacks 240 can be maintained. Thus, positioning thecell stack 240 between the first 210 and second 220 plates can includepositioning a second cell stack between the first 210 and second 220plates.

Various embodiments have been described above. Although the inventionhas been described with reference to these specific embodiments, thedescriptions are intended to be illustrative and are not intended to belimiting. Various modifications and applications may occur to thoseskilled in the art without departing from the true spirit and scope ofthe invention as defined in the appended claims.

1.-25. (Canceled)
 26. A method of forming a battery, the methodcomprising: providing a clamping device; positioning the battery betweenfirst and second plates of the clamping device; adjusting an end portionof a coupling member coupling the first and second plates of theclamping device to set an applied pressure on the battery; allowing atleast one of the first and second plates to move away from the otherplate upon expansion of the battery; and removing the clamping devicefrom the battery after cell formation or cell pretreatment.
 27. Themethod of claim 26, further comprising charging the battery.
 28. Themethod of claim 26, wherein the battery is positioned between the firstand second plates prior to charging the battery for the first time. 29.The method of claim 26, wherein positioning the battery comprisespositioning a second battery between the first and second plates. 30.The method of claim 26, further comprising providing an interfacialmaterial between the battery and at least one of the first and secondplates.
 31. The method of claim 30, wherein the interfacial material isconfigured to conform to a surface of the battery.
 32. The method ofclaim 26, wherein the applied pressure is between about 10 psi and about400 psi.
 33. The method of claim 32, wherein the applied pressure isbetween about 40 psi and about 300 psi.
 34. The method of claim 33,wherein the applied pressure is between about 90 psi and about 300 psi.35. The method of claim 34, wherein the applied pressure is betweenabout 100 psi and about 200 psi.
 36. The method of claim 26, wherein thebattery comprises an anode comprising silicon.
 37. The method of claim26, wherein the battery comprises an anode comprising graphite.
 38. Themethod of claim 26, wherein the battery is a lithium ion battery.